I have an Offenhauser intake and Hedman header installed on my 258 which I need to remove and reinstall to seal up some vacuum leaks.

I ordered a replacement gasket from Hedman, which isn't much to write home about - some kind of pressed cardboard, that seals the intake and exhaust ports.

Hedman

Just in case, I also ordered a gasket kit from FelPro.
The kit had a similar designed gasket, but laminated with a metal facing.
It also had a separate, rubber gasket to seal the intake ports. As well as a couple others

Felpro

So my question is, what gasket(s) do I use??
Sealant/ no sealant? If so which sealant? And where?

I am definitely going to go with the Fel-Pro laminated gasket.
But what about the rubber intake gasket?

I think I have to call their tech Support regarding installation.
One of Fel-Pro's technical documents states:

"....one side is a fiber material and the other side is steel.
Just remember to install the steel side toward the manifold and the fiber side toward the engine block. This allows the exhaust manifold to slide along the steel surface during expansion and contraction without damaging the gasket."

There is no mention of sealant, which I think would eliminate this 'movement'.
I would think a rubber gasket between the intake manifold and exhaust gasket would hinder any 'movement' as well.

The intent of the seperate intake gasket is so the clamping surfaces are flat across. In some cases like John mentioned without using the intake gasket its spaced closer to the head then the exhaust where the cupped washers clamp against the manifolds. In which case the intake never gets the same clamping torque the exhaust gets.

You may need to try mounting with and without it to see how it works for you and your combination of manifolds.

I have the same header on the same engine, and I used the same Fel-Pro gasket set. No sealant. Clamp your headers in a vice. Use a long metal file and file across two of the header inlets at a time. Go slow and keep the file flat. I don't know what you call it, but there is a HUGE file board made to cover all of the inlets at once. Don't know if you can get your hands on one of those. My neighbor has one, so I got lucky. I have no issues with exhaust leaks.

__________________KerrdogGo Fish!<*////><

But the right word at the right time... "Hey, give me a little hug!" That's the difference between lightning and a harmless lightning bug!

It wouldn't hurt to file across the intake runners as well. Same process. You will be able to see the uneven surfaces pretty quickly by the shiny metal. You won't have to do near as much on the aluminum. Just go slow and be deliberate, and you HAVE to go across two or more runners at a time to keep it even between the runners.

Personally, I don't like sealants on the manifold sealing surfaces. Flat mating surfaces, a good gasket, and proper torquing should take care of any issues. My aftermarket Clifford intake does not seal the same as my stock intake. It is much more difficult to eliminate vacuum leaks. A primary cause is that the Belville washers do not sit flat on the runner ears.

__________________KerrdogGo Fish!<*////><

But the right word at the right time... "Hey, give me a little hug!" That's the difference between lightning and a harmless lightning bug!

Same with the Offy. So much so that I had to invert a couple of them to better catch the contact points....

An option there is to carefully grind down the ears so they are even with the exhaust, and you might have to flatten one side of the washer. I was a little concerned about doing that. I'm no engineer, but it is my understanding that a belville washer is designed as a cup to enhance the torque. Turning it over will cause you to lose any gains in a belville washer. I tried using the proper diameter hardened, thickened washers in place of the belvilles, but, ironically, they started to snap in half. So I reinstalled my factory intake. Good to go.

__________________KerrdogGo Fish!<*////><

But the right word at the right time... "Hey, give me a little hug!" That's the difference between lightning and a harmless lightning bug!

An option there is to carefully grind down the ears so they are even with the exhaust, and you might have to flatten one side of the washer. I was a little concerned about doing that. I'm no engineer, but it is my understanding that a belville washer is designed as a cup to enhance the torque. Turning it over will cause you to lose any gains in a belville washer. I tried using the proper diameter hardened, thickened washers in place of the belvilles, but, ironically, they started to snap in half. So I reinstalled my factory intake. Good to go.

Good point!

I have to admit, that when I first started modifications on the jeep i was a bit naive and assumed thing would just bolt on.